This gave me a white background on the content section of the page, and made the transparent brown sidebar into a solid brown color, not sure if you want that but personally I think it looks better and gives more contrast to the sidebar elements.

This I had to change for several CSS rules, you should review your CSS code and merge redundant rules, make use of classes.

I would get rid of that transparent image, and use CSS to color the sidebar instead. If you do want the transparent solution you can apply some CSS code to get a transparent effect, but I would advise you to turn the opacity up a little.